Multnomah County SheriffChristopher Parker was incarcerated for 120 days for sexually abusing a 15-year-old girl for more than a year.

The family of a teenage girl who was sexually abused by a 54-year-old TriMet bus driver has filed suit against the agency, accusing it of failing to train its drivers and staff to prevent such abuse and failing to properly supervise the driver.

The suit, filed this morning in Multnomah County Circuit Court, seeks $1.1 million following the conviction of Christopher Alden Parker for abusing a girl who rode his bus. Parker, who spent 120 days in jail, is now serving a five-year probation term and has to register as a sex offender. He was not named in the suit.

Kelly Clark, lawyer for the girl's guardian, said the girl continues to struggle.

"Like most abuse survivors, she often blames herself in what happened," Clark said in a statement.

The girl was a frequent passenger on Parker's bus, and the two developed a relationship that lasted for more than a year. He was charged with online sexual corruption of a child, a felony, for sending thousands of sexual emails and text messages, and with third-degree sex abuse, a misdemeanor, for kissing her and touching her breasts.

A report by a TriMet employee led to Parker's conviction. The employee saw the girl on out-of-service bus as he drove it to TriMet at the end of his shift. The girl was then seen in Parker's car.

But the lawsuit accuses the agency of being negligent up until that time.

"TriMet knew or should have known that Parker was engaging in a sexually inappropriate relationship with 14-year-old A.C.," the lawsuit says. Parker was reprimanded twice in October 2010 -- one year before his conviction -- by TriMet supervisors for allowing the girl to remain on his bus when it was not in service, the suit says.

"TriMet thus knew that ... Parker was carrying on some type of relationship with a 14-year-old girl and intentionally violating TriMet rules while doing so," the suit says.

It says the agency failed to train its employees to fight sex abuse and stop communication between Parker and the girl. The suit maintains that Parker's union representative knew about the relationship and the reprimands yet did nothing to stop them. Instead, the suit says the official and TriMet employees advised Parker and the girl on how to avoid getting caught. The suit alleges that TriMet employees carried messages between Parker and the girl and that at least one agency employee tried to dissuade the girl from testifying before a grand jury.

TriMet spokeswoman Mary Fetsch said the agency does not comment on litigation.